1. Field of the Invention
The present invention relates to devices intended to reduce unwanted sounds created by internal combustion engines, and more specifically, to structure for decreasing the amount and intensity of sound produced by the air intake of such engines.
2. Description of Related Art
Throughout the world, governments concerned with the spread of noise pollution have enacted or are considering enacting legislation and/or regulations aimed at lessening the amount and effect(s) of that pollution. Those efforts are, in part, directed at limiting sound energy emissions provided by internal combustion engines utilized in both small and large scale vehicles, including emissions produced by grounds-care equipment. To address the restraints imposed by this legislation on permitted emissions levels, industry has sought to reduce the level of noise associated with both the exhaust and air induction systems of these engines.
With regard to the air induction system of internal combustion engines, devices known as air intake silencers have often been used to muffle, and therefore reduce, the noticeability of sound energy caused by these engines. With air as the medium through which sound travels, silencers of this type assist in reducing sound energy created when air is introduced into the engine from the atmosphere. This is in opposition to exhaust systems whereby sound is produced as air exits the engine. This energy often takes the form of noise, the loudness of that noise corresponding to the chosen engine speed upon entry of air into the silencer.
The design of intake silencers has included structure composed of several components requiring connection by welding or other means. For example, one construction includes an open dampening shell having covers welded thereon at its ends. Thereafter, inlet and outlet piping is then attached, by additional welds, to the periphery of apertures provided in the covers for accommodating the flow of air through the shell. Although designs of this type have been capable of performing a silencing function, materials and construction costs remain as areas in which improvement can be viewed as advantageous.
Thus, in order to obtain an economically advantageous construction, there is provided a silencer formed as a one-piece structure. This structure is formed according to the principles of rotational molding thereby reducing the expense of fabrication. Preferably, the mold will be constructed of plastic in the form of cross-linked polyethelene. Alternatively, composite materials could be substituted.
To permit air flow into an engine of vehicle, the silencer is constructed of a main body equipped with an inlet to which suitably fitting tubing can be attached to direct air into the inlet. Paralleling the inlet on an opposing side of the silencer is an outlet through which air is delivered to the engine. Those of ordinary skill in the art will recognize that designation of the inlet and outlet may be interchanged.
Forming the above inlet and outlet are two pipe-like formations molded as part of the overall silencer body. These formations are laterally spaced apart from one another and are substantially similar in the preferred embodiment. Formation of each of the inlet and outlet pipes in this manner enables the main body to be formed from a single mold while also creating an air flow path through the main body. Optimum silencing effect may be achieved by tailoring the dimensions and thus, the volume, of the main body to the engine with which the silencer is to be used. Such tailoring will permit an adequate and appropriately sized flow path so that as air is introduced into the engine during operation, the engine is not starved of air, thereby avoiding engine stall. It is contemplated that the silencer of the instant invention may be used with an engine equipped with either a carburetor or injector fuel delivery system.
Further delivery of air to the engine is accomplished by travel through additional tubing connected to the outlet and to an attached air filter flowing to the engine.
Thus, there is provided a simple and economical air intake silencer allowing for the introduction of air into a vehicle engine while silencing the effect of that entry.